1. Field of the Invention
The present invention relates a small-sized boat, principally to a small-sized boat of the saddle type. More particularly, the present invention relates to improvements in an exhaust manifold of a multiple cylinder engine carried on a small-sized boat.
2. Description of Background Art
Conventionally, a small-sized boat as shown in FIGS. 10(a) and 10(b) is known as a small-sized boat on which a multiple cylinder engine having an exhaust manifold on a side portion thereof is carried as set forth in the Official Gazette publication of Japanese Patent No. 2880680 FIG. 10(a) is a side elevational view, and FIG. 10(b) is a transverse sectional view as viewed from the rear.
The small-sized boat 1 includes a multiple cylinder engine 3 disposed in an internal space of a boat body 2 thereof such that a crankshaft of the multiple cylinder engine 3 extends along forward and rearward directions of the boat body 2.
As shown in FIG. 10(b) and FIG. 11(a), an exhaust manifold 4 is provided on a side portion of the multiple cylinder engine 3.
The exhaust manifold 4 is configured such that, as shown in FIG. 11(b), the lengths of exhaust pipes from connection openings 4a to exhaust ports of the engine 3 to exhaust gas exits at a rear location are substantially equal to one another. To make the lengths equal to one another, the exhaust pipes 4c have ducts which extend forwardly from the exhaust gas exits 4a once and then are curved such that they are directed to the exhaust gas exit 4b at the rear location.
The configuration just described can augment the output power of the engine 3 since the exhaust pipes 4c have no difference in length.
Since the exhaust manifold 4 of the engine 3 in the conventional small-sized boat described above is configured such that the ducts of the exhaust pipes 4c thereof extend forwardly from the exhaust gas exits 4a once they are curved such that they are directed to the exhaust gas exit 4b at the rear location, it has a disadvantage that the exhaust manifold 4 has a large overall size.
It is an object of the present invention to solve such a problem as just described and miniaturize an exhaust manifold of an engine to facilitate disposition of the engine in a boat body.
To attain the object described above, according to the present invention, a small-sized boat wherein a multiple cylinder engine having an exhaust manifold on a side portion thereof is disposed such that a crankshaft thereof extends along forward and rearward directions of a boat body and the exhaust manifold has a structure wherein exhaust pipes connected to exhaust ports of the engine are distributed upwardly and downwardly in such a manner as to form confluence pipes above and below the exhaust ports, and the confluence pipes are further joined to each other to form an exhaust gas exit from the exhaust manifold.
According to the present invention, a small-sized boat includes an exhaust gas exit that is disposed at a substantially central portion in a vertical direction of an internal space of the boat body, and an exhaust gas turbo charger is connected to the exhaust gas exit.
With the small-sized boat according to the present invention, since the multiple cylinder engine having the exhaust manifold on a side portion thereof is disposed such that the crankshaft thereof extends in the forward and rearward directions of the boat body and the exhaust manifold has a structure wherein the exhaust pipes connected to the exhaust ports of the engine are distributed upwardly and downwardly in such a manner as to form the confluence pipes above and below the exhaust ports and the confluence pipes are further joined to each other to form the exhaust gas exit from the exhaust manifold, the exhaust manifold can be miniaturized when compared with the conventional one (FIG. 11(b)).
Describing more particularly, each of the exhaust pipes 4c of the conventional exhaust manifold 4 shown in FIG. 11(b) is configured such that a duct extends forwardly from an exhaust gas exit 4a once and is then curved such that it is directed to the exhaust gas exit 4b at a rear location, and the exhaust pipes 4c are all joined together at the exhaust gas exit 4b. In other words, since the four exhaust pipes 4c are fully independent of each other until they come to the exhaust gas exit 4b, the exhaust manifold 4 cannot be avoided to have a large overall size.
In contrast, in the exhaust manifold in the multiple cylinder engine of the small-sized boat according to the present invention, the exhaust pipes connected to the exhaust ports of the engine are distributed upwardly and downwardly in such a manner as to form the confluence pipes above and below the exhaust ports and the confluence pipes are further joined to each other to form the exhaust gas exit from the exhaust manifold. In other words, since the exhaust pipes distributed upwardly and downwardly with respect to the exhaust ports of the engine are joined together in multiple stages, the exhaust manifold can be miniaturized when compared with the conventional one FIG. 11(b).
Accordingly, with the small-sized boat according to the present invention, the multiple cylinder engine having the exhaust manifold on a side portion thereof can be readily positioned in the boat body.
With the small-sized boat according to the present invention, since the exhaust gas turbo charger in the small-sized boat according to the present invention is connected to the exhaust gas exit, high output power can be obtained.
Further, the exhaust gas exit is disposed at a substantially central portion of the internal space of the boat body in the vertical direction and the exhaust gas turbo charger is connected to the exhaust gas exit. As a result, it is possible to position the exhaust gas turbo charger at a substantially central portion of the internal space of the boat body in the vertical direction, and besides the exhaust gas turbo charger can be readily positioned.
Accordingly, water entering the inside of the boat body is less liable to touch with the exhaust gas turbo charger, and the exhaust gas turbo charger is less likely to be damaged.
In other words, with the small-sized boat according to the present invention, since water entering the inside of the boat body is less liable to touch with the exhaust gas turbo charger while high output power can be obtained by the exhaust gas turbo charger, the exhaust gas turbo charger is less liable to be damaged.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.